1. Field of the Invention:
This invention relates to exposure value display systems for cameras, and, more particularly, to a digital display system for displaying the shutter speed by use of an array of numerical indicators. Still more particularly, it relates to a circuit for controlling the representation of a number with or without selection of a generally accepted time second sign mark which is formed by one of the numerical indicators.
2. Description of the Prior Art:
Use of numerical indicating tubes for generation of the rectilinear "Figure eight" pattern conformed by seven or eight segments is well known in displaying the output signal of an exposure meter in a photographic camera. With the exposure value representative of a shutter speed value, however, because of the display of a fraction of a shutter speed unit, that is, parts of a second, in integer form, it is required to discriminate upon which scale the displayed number is based. This is done either by employing ad added indicating tube adapted only for indicating a symbol such as 1/, as for example, disclosed in DOLS 2,364,851, which appears just to the left of the most significant digit when the numerical value of shutter speed is smaller than indicating tube second, or by utilizing the one (of the plurality numerical indicating tubes) which comes to appear just to the right of the least significant digit in displaying a fraction bar for that discriminating symbol as the central segment is driven alone for energization. For example, the display of a number eight is discriminated as 1/8 and 8- in the former and latter cases respectively when this number happens to mean a reciporocal of 8 seconds. These symbols are however not generally accepted to mean the time unit as in the electrical clock art. For this reason, the beginner in photography often mistakes the displayed number as to whether or not it is longer than one second. Another disadvantage of the conventional digital display employing the symbol indicating tube is to increase the production cost and to decrease the design flexibility.